BREAK out the tin-foil hats – Denis Leary says the new season of FX’s “Rescue Me” will focus on 9/11 conspiracy theories.

Leary dropped the bomb at a book signing in LA Monday night (for his new book, “Why We Suck”) when a fan asked the caustic comic if he believed there should be a reinvestigation into the events leading up to and surrounding the 9/11 terror attacks.